CN110161303B - Microwave load for 0-6GHz calorimetric microwave power meter - Google Patents
Microwave load for 0-6GHz calorimetric microwave power meter Download PDFInfo
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- CN110161303B CN110161303B CN201910516280.4A CN201910516280A CN110161303B CN 110161303 B CN110161303 B CN 110161303B CN 201910516280 A CN201910516280 A CN 201910516280A CN 110161303 B CN110161303 B CN 110161303B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/20—Modifications of basic electric elements for use in electric measuring instruments; Structural combinations of such elements with such instruments
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R21/00—Arrangements for measuring electric power or power factor
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Abstract
The invention discloses a microwave load for a 0-6GHz calorimetric microwave power meter, which comprises the following components: the device comprises a microwave load circuit, a liquid circulation and heat conduction channel, a liquid channel interface, a microwave load circuit interface, a heat insulation device and a sealed shell; the heat insulation device and the microwave load circuit are both of cavity structures, the microwave load circuit is fixed in an inner cavity of the heat insulation device, and a liquid channel interface and a microwave load circuit interface are reserved on the heat insulation device; one end of a cavity in the microwave load circuit is connected with a microwave load circuit interface, a liquid circulation and heat conduction channel is positioned in the cavity of the microwave load circuit, the liquid circulation and heat conduction channel is tightly attached to the microwave load circuit, and two ends of the liquid circulation and heat conduction channel are connected with the liquid channel interface; the method solves the problems that the microwave millimeter wave power from several watts to hundreds of watts cannot be measured by direct measurement and a high-power water load method, and the precision of a coupling measurement method is not enough.
Description
Technical Field
The invention relates to the field of microwave power measurement, in particular to a microwave load for a 0-6GHz calorimetric microwave power meter.
Background
Accurate measurement of medium and low microwave power is very important for industrial production and defense technology, and generally, small microwave power (in milliwatt order) can be directly and accurately measured through existing commercial equipment. When the microwave with medium and low power (several watts to hundreds of watts) is measured, a small-power microwave with equal proportion can be obtained through the directional coupler, then the small-power microwave is directly measured, and then the microwave power is obtained according to the coupling coefficient of a used device, but the coupling coefficient of the device can be changed under different frequencies and different powers, so that the measurement accuracy is not high. The calorimetric water load can also be used for microwave power measurement, water flowing at a certain speed of the load is used as a microwave absorbing medium, microwave energy is lost in the water and converted into heat energy of the water, and the microwave power can be calculated through a formula by measuring the temperature difference of an inlet and an outlet of the water load. The measurement method is not suitable for low-frequency microwaves (such as below 1 GHz) because the size of a cavity with corresponding frequency is large, and secondly, the measurement method is used for high-power microwave millimeter wave measurement at present, the power is generally above kilowatt level, otherwise, the precision cannot be guaranteed.
Disclosure of Invention
The invention provides a microwave load for a 0-6GHz calorimetric microwave power meter, and aims to solve the problems that the microwave millimeter wave power from several watts to hundreds of watts cannot be measured by direct measurement and a high-power water load method, and the precision of a coupling measurement method is not enough.
In order to achieve the above object, the present application provides a 0-6GHz calorimetric medium-low power microwave load, which comprises:
microwave load circuit, liquid circulation and heat conduction channel, liquid channel interface, microwave load circuit interface, adiabatic device. The heat insulating device is box-shaped, all parts of the system are wrapped in the heat insulating device, and a liquid channel interface and a microwave load circuit interface are reserved. The microwave load circuit is in a cavity structure, one end of the cavity is connected with a microwave load circuit interface, the microwave load circuit is tightly attached to the liquid circulation and heat conduction channel, and the liquid channel interface is connected to the two ends of the liquid circulation and heat conduction channel so that liquid can flow in and out;
the microwave load circuit is a microwave absorption circuit consisting of a metal cavity, a transmission line, an attenuator and a microwave resistor. The transmission line can be microstrip line, coaxial line etc. attenuator and microwave resistance install inside the cavity, and the cavity ground connection, microwave signal gets into the attenuator in advance through the transmission line by the cavity entry, then gets into microwave resistance through the transmission line, and wherein the attenuator can be 0 or more, uses the transmission line to connect between the attenuator equally. The broadband microwave power supply has the characteristic of low standing wave ratio of 0-6GHz in a broadband, namely, only a tiny part of microwave energy is reflected back, and the microwave energy is ensured to be absorbed by a load circuit and converted into heat energy;
the microwave load circuit interface is a coaxial interface, so that the microwave load circuit can be connected with a coaxial waveguide with a specific specification in a matching way, and the lowest reflection and loss in the transmission process of microwave energy are ensured.
The liquid circulation and the heat conduction channel are tightly attached to the part of the microwave load circuit generating heat, so that the liquid medium can uniformly flow in the channel and absorb heat energy, and a stable temperature difference can be formed at the inlet and the outlet of the liquid channel when the system works normally, wherein the liquid medium can be water, alcohol, kerosene, ether and the like.
The liquid channel interface consists of a liquid inlet and a liquid outlet, wherein the liquid inlet is far away from the part of the microwave load circuit generating heat as far as possible, so that the heat energy is prevented from being conducted to the liquid inlet through the liquid or the wall of the liquid channel. And the liquid outlet is far away from the microwave load circuit interface part as far as possible, so that the heat energy is prevented from being conducted to the outside through the microwave load circuit interface.
The heat insulation device is of a cavity structure and is made of heat insulation materials or metal vacuum technology, the microwave load circuit, the liquid circulation and heat conduction channel are wrapped in the heat insulation device, a liquid channel interface and a microwave load circuit interface are reserved and can be connected with the outside, and heat energy generated by the microwave load circuit is guaranteed not to exchange heat with the outside as much as possible.
Wherein, millimeter wave calorimetric microwave power meter includes:
the load module, the circulating constant temperature module, the 2 temperature measuring modules, the data acquisition and post-processing module, the flowmeter module and the controller module are arranged in the pipeline;
the load is of a cavity structure, the cavity structure absorbs and converts electromagnetic field energy of millimeter waves generated by the millimeter wave power source to be tested into heat and transfers the heat to the cavity wall, and a liquid medium channel is arranged on the cavity wall;
the circulating constant temperature module is used for generating liquid circulation, continuously taking away heat generated by the load and controlling the temperature of the liquid at the inlet of the load to be constant;
the 2 temperature measuring modules are respectively used for measuring the temperature of liquid flowing into the load inlet and the temperature of liquid flowing out of the load outlet;
a flow meter and controller module for controlling and measuring the flow of the liquid;
and the data acquisition and post-processing module is used for acquiring the temperature data measured by the 2 temperature measurement modules and the flow data measured by the flowmeter and the controller module into a computer or an embedded system, and obtaining the microwave power value through calculation.
One or more technical solutions provided by the present application have at least the following technical effects or advantages:
1. the invention overcomes the problems that the microwave power of several watts to several hundred watts can not be measured by direct measurement and high-power water load, and the precision of a coupling measurement method or an attenuation measurement method is not enough.
2. The invention has the advantages of large measurable microwave frequency bandwidth and large usable range.
3. The invention can adjust the flow speed of the liquid medium in the load according to the measured microwave power so as to widen the power measurement range and achieve the optimal measurement precision.
4. The microwave load circuit can work under the direct current state, and the direct current power is easy to accurately control and measure, so that the load can be directly calibrated under the direct current working state, the power absorption and calibration of microwave and millimeter waves are integrated, and the measurement precision is improved.
5. The outermost layer of the invention is designed to be insulated, thus further improving the measurement precision.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention;
FIG. 1 is a schematic structural diagram of a microwave load for the 0-6GHz calorimetric microwave power meter;
FIG. 2 is a schematic diagram of a microwave load circuit;
FIG. 3 is a three-dimensional view of the liquid circulation and heat conduction channel, the liquid channel interface and the microwave load circuit cavity structure;
fig. 4 is a schematic composition diagram of a microwave power meter.
Detailed Description
In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflicting with each other.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described and thus the scope of the present invention is not limited by the specific embodiments disclosed below.
The system structure of the invention is shown in fig. 1, and comprises a liquid channel inlet 101, a liquid channel outlet 102, a liquid circulation heat conduction channel 103, a microwave load circuit interface 104, a microwave load circuit 105, a microwave load circuit cavity 106, and a heat insulation device 107. The liquid medium used is water.
A specific microwave absorption equivalent circuit is shown in fig. 2. The microwave load circuit comprises an equivalent coaxial N-type interface 201, a 1.5dB pi-type attenuator 202 (consuming 25% of energy), a 1.5dB pi-type attenuator 203 (consuming 25% of energy), a 50-ohm microwave resistor 204 (consuming 50% of energy), and a grounded microwave load circuit cavity 205. The attenuator, the microwave resistor and the coaxial N-type interface are connected by a microstrip line with characteristic impedance of 50 ohms, the input end impedance of the attenuator is 50 ohms after debugging in the frequency range of 0-6GHz, the standing-wave ratio is less than 1.25, and the standing-wave ratio of 0-3GHz is less than 1.15.
The specific liquid circulation and heat conduction channel, the liquid channel interface and the microwave load circuit cavity form an integral oxygen-free copper metal structure through machining and welding, the size is 25cm x 3cm x 2cm, and the structure is shown in figure 3. Comprises a microwave loading circuit cavity 301, a microwave absorption circuit placing position 302, a liquid channel outlet 303, a liquid channel inlet 304 and a liquid circulation and heat conduction channel 305.
Wherein heat insulation device is cuboid cavity structures, and the size is 30cm 10cm by 10cm, is made by the glass fiber board that has thermal-insulated effect, fixes microwave load circuit, liquid circulation and heat conduction channel wherein and reserves liquid channel interface and microwave load circuit interface and can meet with the external world, and sealed cavity reduces inside gaseous heat convection simultaneously, has guaranteed the thermal-insulated effect of heat insulation device.
The liquid channel interfaces are NPT-1/8 threaded interfaces, the liquid channel inlet is close to the microwave load circuit interface, the liquid channel outlet is on the other side, the attenuator and the resistor for generating heat energy are closely attached to the metal wall of the microwave load circuit cavity close to the liquid channel, the liquid circulation and the heat conduction channel enable the liquid to flow in a winding and bending mode and take away the heat energy generated by the microwave resistor and the attenuator (the curve arrow in the figure is the liquid flow direction), and when the system works, the liquid forms a stable temperature difference between the liquid channel inlet and the liquid channel outlet.
Referring to fig. 4, the millimeter wave calorimetric microwave power meter includes:
the load module, the circulating constant temperature module, the 2 temperature measuring modules, the data acquisition and post-processing module, the flowmeter module and the controller module are arranged in the pipeline;
the load is of a cavity structure, the cavity structure absorbs and converts electromagnetic field energy of millimeter waves generated by the millimeter wave power source to be tested into heat and transfers the heat to the cavity wall, and a liquid medium channel is arranged on the cavity wall;
the circulating constant temperature module is used for generating liquid circulation, continuously taking away heat generated by the load and controlling the temperature of the liquid at the inlet of the load to be constant;
the 2 temperature measuring modules are respectively used for measuring the temperature of liquid flowing into the load inlet and the temperature of liquid flowing out of the load outlet;
a flow meter and controller module for controlling and measuring the flow of the liquid;
and the data acquisition and post-processing module is used for acquiring the temperature data measured by the 2 temperature measurement modules and the flow data measured by the flowmeter and the controller module into a computer or an embedded system, and obtaining the microwave power value through calculation.
In the embodiment of the present application, the liquid medium in the millimeter wave calorimetric microwave power meter is purified water, alcohol, kerosene or diethyl ether.
Wherein, in this application embodiment, millimeter wave calorimetric microwave power meter mesocycle constant temperature module includes: a thermostat, a liquid medium transmission channel and a circulating pump; the head end and the tail end of the liquid medium transmission channel are respectively connected with the load liquid inlet and the load liquid outlet, the thermostat is used for controlling the temperature of liquid, and the circulating pump is used for generating circulating power.
In the embodiment of the present application, in the millimeter wave calorimetric microwave power meter, temperature data measured by 2 temperature measurement modules and flow data measured by a flowmeter and a controller module are collected into a computer or an embedded system, and a microwave power value is obtained through calculation, specifically:
according to the thermodynamic formula:
Q＝C·m·ΔT (1)
wherein: q heat, power, in joules (J)
Specific heat capacity, assuming that the medium is water, the specific heat capacity of water is as follows: 4200 Job/(kg. degree. C.), (J/(kg. degree. C.))
m is mass in kilogram (kg)
Delta T is the absolute value of the temperature change in degrees centigrade and DEG C.
After transformation, the formula (1) can be changed into:
P＝70·Δv·ΔT (2)
p is the measured power value in watts and Δ v is the flow rate in units of: liter/minute (L/min)
According to the formula (2), the power can be conveniently obtained by calculating the measured temperature difference and the water flow.
In the embodiment of the application, a method for measuring medium and low power in a calorimetric millimeter wave is further provided based on a millimeter wave calorimetric microwave power meter, and the method comprises the following steps:
step 1: calibrating the low power measurement system;
step 2: connecting a millimeter wave power source to be tested with the load, and transmitting millimeter waves generated by the millimeter wave power source to be tested to the load;
and step 3: controlling the temperature and flow rate of the liquid through a circulating constant temperature module;
and 4, step 4: the reason is that the data acquisition and post-processing module acquires the temperature data measured by the 2 temperature measurement modules and the flow data measured by the flowmeter and the controller module, and the microwave power value of the millimeter wave power source to be measured is calculated based on the acquired data.
The load in the millimeter wave calorimetric microwave power meter is of a cavity structure, a millimeter wave absorbing material composed of carbon powder and graphite nano materials is arranged in the cavity, the energy of millimeter waves is converted into heat energy in the absorbing material, and then the heat energy is transferred to a liquid medium in a winding liquid channel through the cavity, wherein the liquid medium can be water, alcohol, kerosene, ether and the like.
The millimeter wave calorimetric microwave power meter overcomes the problems that the millimeter wave power from a few watts to a few hundred watts cannot be measured by a direct measurement method and a high-power water load method, and the precision of a coupling measurement method is not enough.
The millimeter wave calorimetric microwave power meter adopts the constant temperature module in the circulating liquid channel, ensures the constant temperature of the liquid at the inlet of the power absorption module, ensures the stability of the inlet temperature, is favorable for the stability of a temperature measurement system, and is favorable for improving the precision and the stability of power measurement.
The millimeter wave calorimetric microwave power meter adopts an ultrahigh precision temperature measurement module, a high precision low flow rate flowmeter and a controller to realize millimeter wave calorimetric measurement of several watts to several hundred watts.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (9)
1. A microwave load for a 0-6GHz calorimetric microwave power meter, characterized in that the load comprises:
the device comprises a microwave load circuit, a liquid circulation and heat conduction channel, a liquid channel interface, a microwave load circuit interface, a heat insulation device and a sealing shell;
the heat insulation device and the microwave load circuit are both of cavity structures, the microwave load circuit is fixed in an inner cavity of the heat insulation device, and a liquid channel interface and a microwave load circuit interface are reserved on the heat insulation device; one end of the cavity in the microwave load circuit is connected with the microwave load circuit interface, the liquid circulation and heat conduction channel is positioned in the cavity of the microwave load circuit, the liquid circulation and heat conduction channel is tightly attached to the microwave load circuit, and two ends of the liquid circulation and heat conduction channel are connected with the liquid channel interface.
2. The microwave load for a 0-6GHz calorimetric microwave power meter according to claim 1, wherein the microwave load circuit comprises: a metal cavity, a transmission line and a microwave resistor; the microwave signal enters the microwave resistor from the inlet of the metal cavity through the transmission line.
3. The microwave load for the 0-6GHz calorimetric microwave power meter according to claim 2, wherein the microwave load circuit further comprises a plurality of attenuators connected in series in sequence, and the microwave signal enters the plurality of attenuators from the inlet of the metal cavity through the transmission line in sequence and then enters the microwave resistor through the transmission line.
4. The microwave load for a 0-6GHz calorimetric microwave power meter according to claim 2, wherein the transmission line is a microstrip line or a coaxial line.
5. The microwave load for the 0-6GHz calorimetric microwave power meter according to claim 3, wherein the attenuators are connected by a transmission line.
6. The microwave load for a 0-6GHz calorimetric microwave power meter according to claim 1, wherein the microwave load circuit interface is a coaxial interface.
7. The microwave load for the 0-6GHz calorimetric microwave power meter according to claim 1, wherein the liquid medium in the liquid circulation and heat conduction channel is water or alcohol or kerosene or ether.
8. A microwave load for a 0-6GHz calorimetric microwave power meter according to claim 1, wherein the fluid passage interface comprises a fluid inlet and a fluid outlet, wherein the fluid inlet is remote from the portion of the microwave load circuit from which heat is generated and the fluid outlet is remote from the portion of the microwave load circuit interface.
9. A microwave load for a 0-6GHz calorimetric microwave power meter according to claim 1, wherein the thermal insulation means is made of a thermally insulating material or a metal vacuum process.
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| CN110161303B true CN110161303B (en) | 2020-12-01 |
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| US8866271B2 (en) * | 2010-10-07 | 2014-10-21 | Hitachi Kokusai Electric Inc. | Semiconductor device manufacturing method, substrate processing apparatus and semiconductor device |
| CN201973886U (en) * | 2010-12-02 | 2011-09-14 | 长春黄金研究院 | Microwave liquid circulation heating device |
| CN102354786A (en) * | 2011-10-21 | 2012-02-15 | 湖北汉鑫源真空电子科技有限公司 | C-band high-energy silicon carbide ceramic microwave load |
| CN105143841A (en) * | 2013-02-22 | 2015-12-09 | 伯德技术集团股份有限公司 | Microfabricated calorimeter for RF power measurement |
| CN105140607A (en) * | 2015-07-22 | 2015-12-09 | 江苏大丰港和顺科技有限公司 | Water-cooled microwave waveguide suitable for high-power microwave heating equipment |
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